The division structure is intended to provide a set of minimum requirements for a league, including number of teams, geographic distribution of teams, market size of a team's city, stadium capacity, as well as the minimum financial requirements for team owners.

The USSF had given the NASL -- which began in its current incarnation in 2011 -- numerous waivers over the years, and after the NASL lost four teams following the 2016 season, the USSF granted the NASL provisional Division II status in early 2017, provided it met certain conditions. It did the same for the United Soccer League, which prior to this year had operated as a Division III league.

When those conditions, among them that the NASL expand to 12 teams, were not met, the USSF decided to reject the NASL's application.

Rocco B. Commisso, chairman of the NASL's Board of Governors and the principal owner of the New York Cosmos, which plays its home games in Brooklyn, said after the filing: "The USSF left the NASL no choice except to file this lawsuit.

"The NASL has taken this step to protect not just the league, but also the game, fans, and everyone with a stake in the future success of professional soccer leagues based in this country."

The NASL's complaint alleges that the USSF has violated federal antitrust laws through its anticompetitive "division" structure that splits men's professional soccer for U.S.-based leagues based on what the NASL describes as "arbitrary criteria that the USSF has manipulated to favor Major League Soccer (MLS), which is the commercial business partner of the USSF."

The release also said that the USSF's business arrangements "include multi-million dollar media and marketing contracts with Soccer United Marketing (SUM), MLS's marketing arm that also jointly sells and markets MLS rights combined with rights to U.S. national soccer teams operated by the USSF."

The complaint alleges that the USSF has selectively applied and waived its divisional criteria to suppress competition from the NASL, both against MLS and USL.

For example, under the USSF's divisional criteria, there are European clubs that have successfully operated for decades that would be considered ineligible for "Division I" or even "Division II" status because of arbitrary requirements like stadium capacity and market size.

The complaint alleges that the USSF sought to limit competition from the NASL to MLS and USL, and now seeks to destroy the NASL by arbitrarily revoking the NASL's Division II status for the upcoming season.

The complaint only seeks injunctive relief against the USSF's conduct regarding its divisional designations.